Redefinition of tricuspid valve structures for successful ring annuloplasty.

Background: Although numerous reports have described suturing techniques for tricuspid annuloplasty, most studies were not based on a detailed anatomy of the tricuspid annulus. Thus, the definition of the tricuspid commissures remains unclear. This study aimed to clearly define the commissures and leaflets of the tricuspid valve and subvalvular structures, and to define a standard method for tricuspid annuloplasty.

Methods: In 27 normal heart specimens without cardiac disease, the tricuspid commissure was defined using indentations of the leaflets as a point, not an area, and the length of each tricuspid annulus was measured. The relationships between the leaflets and the subvalvular structures were then examined.

Results: In most specimens, the posterior leaflet had 2 (62.9%) or 3 (29.6%) scallops, providing further evidence of posterior leaflet diversity. In addition, the posterior leaflet had 1 or 2 indentations, which can be mistaken for true commissures. The annulus of the posterior leaflet was significantly longer than the annuli of the other 2 leaflets (P < .00428). The annuli of the septal and the anterior leaflets were supported by the interventricular septum and the supraventricular crest, respectively, whereas the posterior leaflet annulus was distributed largely along the right ventricular free wall.

Conclusions: There was a structural gap between the tricuspid leaflet indentations and the subvalvular structures. The relationships among the leaflets, commissures, and subvalvular structures differed in the septal, anterior, and posterior leaflets. This new definition of the commissural point may aid the development of a clear-cut methodology for prosthetic ring annuloplasty.